[The effect of exercise on the pharmacokinetics of acetaminophen and acetylsalicylic acid].
The influence of exercise on the pharmacokinetics of drugs is not sufficiently apparent. Therefore the purpose of my study was to evaluate the influence of standardized exercise on pharmacokinetics of acetaminophen and acetylsalicylic acid (ASA) and also to establish whether moderate (submaximal) exercise demands modification involving the doses of these drugs. That was studied in 20 healthy young (ranging in age 22-42 years) male subjects receiving acetaminophen or ASA, 1 g orally. All subjects were non-smokers who abstained from using caffeine and alcohol 2 weeks before and in the period of study, which consisted of two parts: resting trials and exercise trials. Exercise trials: treadmill walking--3 mph (4.8 km/h), 20 minutes per half an hour for 3 hours (50% VO2max). On the rest day volunteers stayed in the supine or sitting position for the same period. Blood samples were collected from a forearm (antecubital) vein through an indwelling cannula. Acetaminophen and ASA plasma concentrations were determined by FPIA. The plasma level-time curves were fitted according to one compartment open pharmacokinetic model. Plasma concentrations measured (7 days) before and after the physical exercise, did not demonstrate statistically significant differences (Fig. 1, 2). The results of this study indicate that the pharmacokinetics of single doses of acetaminophen and ASA are independent of submaximal physical exercise. There were no significant differences between the rest and the exercise day in the pharmacokinetic parameters of acetaminophen and ASA (Fig. 3). Since both drugs belong to the group whose elimination is not due to the liver flow, it is not surprising that its total body clearance, and its half-life of elimination were unaffected by physical exercise. The minor changes in haematocrit, plasma protein, free fatty acids, levels which were reported are probably not sufficient to modify the disposition of these drugs. Therefore, there is no need for dose adjustment in patient who moderately exercises (50% VO2max). A little change in pharmacokinetics parameters of acetaminophen and ASA could arise due to some differences of its physical and chemical properties. Without further studies on this subject, the explanation of that finding remains very much speculative.
Sawrymowicz
M
M
Z Katedry Farmakologii Klinicznej i Toksykologii Pomorskiej Akademii Medycznej w Szczecinie, Szczecin.
D000082:Acetaminophen / Q000008:administration & dosage / Q000097:blood*; D000284:Administration, Oral; D000328:Adult; D001241:Aspirin / Q000008:administration & dosage / Q000097:blood*; D001798:Blood Proteins / Q000032:analysis / Q000187:drug effects; D015444:Exercise / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006207:Half-Life; D006400:Hematocrit; D006801:Humans; D008297:Male; D012016:Reference Values
D001798:Blood Proteins; D005230:Fatty Acids, Nonesterified; D000082:Acetaminophen; D001241:Aspirin
Wpływ wysiłku fizycznego na farmakokinetyke acetaminofenu i kwasu acetylosalicylowego.